\documentclass{ctexbook}
\usepackage{amsfonts}
\usepackage{amsmath}
\usepackage{mathabx}
\usepackage{graphicx}
\usepackage{amsthm}
\ctexset{
%chapter/format = \sffamily\raggedright,
section/format += \sffamily\raggedright,
subsection/format += \fbox,
}

% 中文定理环境
% \indent 为了段前空两格
\newtheorem{theorem}{\indent 定理}[section]
\newtheorem{lemma}[theorem]{\indent 引理}
\newtheorem{proposition}[theorem]{\indent 命题}
\newtheorem{corollary}[theorem]{\indent 推论}
\newtheorem{definition}{\indent 定义}[section]
\newtheorem{example}{\indent 例}[chapter]
\newtheorem{remark}{\indent 注}[section]
\newenvironment{solution}{\begin{proof}[\indent\bf 解]}{\end{proof}}
\renewcommand{\proofname}{\indent\bf 证明}





\begin{document}
\title{模糊集的概念与应用}
\author{Michal Jezewski }
\maketitle

\tableofcontents

\input{ch01/ch01.tex}

\end{document}